Feat/lifecycle hooks (#351)
* feat(update): add lifecycle hooks to the update action * fix(ci): add bash tests for lifecycle-hooks to the ci workflow * fix(ci): move integration tests to an isolated step * fix(ci): fix malformed all-contributors json * fix(ci): disable automatic bash test until we figure out a reasonable way to run it in circlecipull/353/head
Simon Aronsson
5 years ago
committed by
GitHub
parent
874180a518
commit
bfae38dbf8
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## Executing commands before and after updating
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> **DO NOTE**: Both commands are shell commands executed with `sh`, and therefore require the
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> container to provide the `sh` executable.
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It is possible to execute a *pre-update* command and a *post-update* command
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**inside** every container updated by watchtower. The *pre-update* command is
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executed before stopping the container, and the *post-update* command is
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executed after restarting the container.
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This feature is disabled by default. To enable it, you need to set the option
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`--enable-lifecycle-hooks` on the command line, or set the environment variable
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`WATCHTOWER_LIFECYCLE_HOOKS` to true.
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### Specifying update commands
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The commands are specified using docker container labels, with
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`com.centurylinklabs.watchtower.pre-update-command` for the *pre-update*
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command and `com.centurylinklabs.watchtower.lifecycle.post-update` for the
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*post-update* command.
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These labels can be declared as instructions in a Dockerfile:
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```docker
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LABEL com.centurylinklabs.watchtower.lifecycle.pre-update="/dump-data.sh"
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LABEL com.centurylinklabs.watchtower.lifecycle.post-update="/restore-data.sh"
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```
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Or be specified as part of the `docker run` command line:
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```bash
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docker run -d \
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--label=com.centurylinklabs.watchtower.lifecycle.pre-update="/dump-data.sh" \
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--label=com.centurylinklabs.watchtower.lifecycle.post-update="/restore-data.sh" \
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someimage
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```
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### Execution failure
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The failure of a command to execute, identified by an exit code different than
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0, will not prevent watchtower from updating the container. Only an error
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log statement containing the exit code will be reported.
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@ -0,0 +1,39 @@
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package container
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const (
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watchtowerLabel = "com.centurylinklabs.watchtower"
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signalLabel = "com.centurylinklabs.watchtower.stop-signal"
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enableLabel = "com.centurylinklabs.watchtower.enable"
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zodiacLabel = "com.centurylinklabs.zodiac.original-image"
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preUpdateLabel = "com.centurylinklabs.watchtower.lifecycle.pre-update"
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postUpdateLabel = "com.centurylinklabs.watchtower.lifecycle.post-update"
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)
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// GetLifecyclePreUpdateCommand returns the pre-update command set in the container metadata or an empty string
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func (c Container) GetLifecyclePreUpdateCommand() string {
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return c.getLabelValueOrEmpty(preUpdateLabel)
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}
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// GetLifecyclePostUpdateCommand returns the post-update command set in the container metadata or an empty string
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func (c Container) GetLifecyclePostUpdateCommand() string {
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return c.getLabelValueOrEmpty(postUpdateLabel)
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}
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// ContainsWatchtowerLabel takes a map of labels and values and tells
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// the consumer whether it contains a valid watchtower instance label
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func ContainsWatchtowerLabel(labels map[string]string) bool {
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val, ok := labels[watchtowerLabel]
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return ok && val == "true"
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}
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func (c Container) getLabelValueOrEmpty(label string) string {
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if val, ok := c.containerInfo.Config.Labels[label]; ok {
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return val
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}
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return ""
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}
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func (c Container) getLabelValue(label string) (string, bool) {
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val, ok := c.containerInfo.Config.Labels[label]
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return val, ok
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}
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@ -0,0 +1,208 @@
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#!/usr/bin/env bash
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set -e
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IMAGE=server
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CONTAINER=server
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LINKED_IMAGE=linked
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LINKED_CONTAINER=linked
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WATCHTOWER_INTERVAL=2
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function remove_container {
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docker kill $1 >> /dev/null || true && docker rm -v $1 >> /dev/null || true
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}
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function cleanup {
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# Do cleanup on exit or error
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echo "Final cleanup"
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sleep 2
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remove_container $CONTAINER
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remove_container $LINKED_CONTAINER
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pkill -9 -f watchtower >> /dev/null || true
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}
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trap cleanup EXIT
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DEFAULT_WATCHTOWER="$(dirname "${BASH_SOURCE[0]}")/../watchtower"
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WATCHTOWER=$1
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WATCHTOWER=${WATCHTOWER:-$DEFAULT_WATCHTOWER}
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echo "watchtower path is $WATCHTOWER"
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##################################################################################
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##### PREPARATION ################################################################
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##################################################################################
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# Create Dockerfile template
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DOCKERFILE=$(cat << EOF
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FROM node:alpine
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LABEL com.centurylinklabs.watchtower.lifecycle.pre-update="cat /opt/test/value.txt"
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LABEL com.centurylinklabs.watchtower.lifecycle.post-update="echo image > /opt/test/value.txt"
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ENV IMAGE_TIMESTAMP=TIMESTAMP
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WORKDIR /opt/test
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ENTRYPOINT ["/usr/local/bin/node", "/opt/test/server.js"]
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EXPOSE 8888
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RUN mkdir -p /opt/test && echo "default" > /opt/test/value.txt
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COPY server.js /opt/test/server.js
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EOF
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)
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# Create temporary directory to build docker image
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TMP_DIR="/tmp/watchtower-commands-test"
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mkdir -p $TMP_DIR
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# Create simple http server
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cat > $TMP_DIR/server.js << EOF
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const http = require("http");
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const fs = require("fs");
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http.createServer(function(request, response) {
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const fileContent = fs.readFileSync("/opt/test/value.txt");
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response.writeHead(200, {"Content-Type": "text/plain"});
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response.write(fileContent);
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response.end();
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}).listen(8888, () => { console.log('server is listening on 8888'); });
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EOF
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function builddocker {
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TIMESTAMP=$(date +%s)
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echo "Building image $TIMESTAMP"
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echo "${DOCKERFILE/TIMESTAMP/$TIMESTAMP}" > $TMP_DIR/Dockerfile
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docker build $TMP_DIR -t $IMAGE >> /dev/null
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}
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# Start watchtower
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echo "Starting watchtower"
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$WATCHTOWER -i $WATCHTOWER_INTERVAL --no-pull --stop-timeout 2s --enable-lifecycle-hooks $CONTAINER $LINKED_CONTAINER &
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sleep 3
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echo "#################################################################"
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echo "##### TEST CASE 1: Execute commands from base image"
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echo "#################################################################"
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# Build base image
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builddocker
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# Run container
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docker run -d -p 0.0.0.0:8888:8888 --name $CONTAINER $IMAGE:latest >> /dev/null
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sleep 1
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echo "Container $CONTAINER is runnning"
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# Test default value
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RESP=$(curl -s http://localhost:8888)
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if [ $RESP != "default" ]; then
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echo "Default value of container response is invalid" 1>&2
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exit 1
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fi
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# Build updated image to trigger watchtower update
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builddocker
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WAIT_AMOUNT=$(($WATCHTOWER_INTERVAL * 3))
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echo "Wait for $WAIT_AMOUNT seconds"
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sleep $WAIT_AMOUNT
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# Test value after post-update-command
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RESP=$(curl -s http://localhost:8888)
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if [[ $RESP != "image" ]]; then
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echo "Value of container response is invalid. Expected: image. Actual: $RESP"
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exit 1
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fi
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remove_container $CONTAINER
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echo "#################################################################"
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echo "##### TEST CASE 2: Execute commands from container and base image"
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echo "#################################################################"
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# Build base image
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builddocker
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# Run container
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docker run -d -p 0.0.0.0:8888:8888 \
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--label=com.centurylinklabs.watchtower.lifecycle.post-update="echo container > /opt/test/value.txt" \
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--name $CONTAINER $IMAGE:latest >> /dev/null
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sleep 1
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echo "Container $CONTAINER is runnning"
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# Test default value
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RESP=$(curl -s http://localhost:8888)
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if [ $RESP != "default" ]; then
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echo "Default value of container response is invalid" 1>&2
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exit 1
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fi
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# Build updated image to trigger watchtower update
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builddocker
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WAIT_AMOUNT=$(($WATCHTOWER_INTERVAL * 3))
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echo "Wait for $WAIT_AMOUNT seconds"
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sleep $WAIT_AMOUNT
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# Test value after post-update-command
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RESP=$(curl -s http://localhost:8888)
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if [[ $RESP != "container" ]]; then
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echo "Value of container response is invalid. Expected: container. Actual: $RESP"
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exit 1
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fi
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remove_container $CONTAINER
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echo "#################################################################"
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echo "##### TEST CASE 3: Execute commands with a linked container"
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echo "#################################################################"
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# Tag the current image to keep a version for the linked container
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docker tag $IMAGE:latest $LINKED_IMAGE:latest
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# Build base image
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builddocker
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# Run container
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docker run -d -p 0.0.0.0:8888:8888 \
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--label=com.centurylinklabs.watchtower.lifecycle.post-update="echo container > /opt/test/value.txt" \
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--name $CONTAINER $IMAGE:latest >> /dev/null
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docker run -d -p 0.0.0.0:8989:8888 \
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--label=com.centurylinklabs.watchtower.lifecycle.post-update="echo container > /opt/test/value.txt" \
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--link $CONTAINER \
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--name $LINKED_CONTAINER $LINKED_IMAGE:latest >> /dev/null
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sleep 1
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echo "Container $CONTAINER and $LINKED_CONTAINER are runnning"
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# Test default value
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RESP=$(curl -s http://localhost:8888)
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if [ $RESP != "default" ]; then
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echo "Default value of container response is invalid" 1>&2
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exit 1
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fi
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# Test default value for linked container
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RESP=$(curl -s http://localhost:8989)
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if [ $RESP != "default" ]; then
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echo "Default value of linked container response is invalid" 1>&2
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exit 1
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fi
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# Build updated image to trigger watchtower update
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builddocker
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WAIT_AMOUNT=$(($WATCHTOWER_INTERVAL * 3))
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echo "Wait for $WAIT_AMOUNT seconds"
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sleep $WAIT_AMOUNT
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# Test value after post-update-command
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RESP=$(curl -s http://localhost:8888)
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if [[ $RESP != "container" ]]; then
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echo "Value of container response is invalid. Expected: container. Actual: $RESP"
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exit 1
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fi
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# Test that linked container did not execute pre/post-update-command
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RESP=$(curl -s http://localhost:8989)
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if [[ $RESP != "default" ]]; then
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echo "Value of linked container response is invalid. Expected: default. Actual: $RESP"
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exit 1
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fi
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