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119 lines
4.0 KiB
Markdown
119 lines
4.0 KiB
Markdown
Watchtower supports private Docker image registries. In many cases, accessing a private registry requires a valid username and password (i.e., _credentials_). In order to operate in such an environment, watchtower needs to know the credentials to access the registry.
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The credentials can be provided to watchtower in a configuration file called `config.json`. There are two ways to generate this configuration file:
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* The configuration file can be created manually.
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* Call `docker login <REGISTRY_NAME>` and share the resulting configuration file.
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### Create the configuration file manually
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Create a new configuration file with the following syntax and a base64 encoded username and password `auth` string:
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```json
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{
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"auths": {
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"<REGISTRY_NAME>": {
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"auth": "XXXXXXX"
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}
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}
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}
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```
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`<REGISTRY_NAME>` needs to be replaced by the name of your private registry (e.g., `my-private-registry.example.org`)
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The required `auth` string can be generated as follows:
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```bash
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echo -n 'username:password' | base64
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```
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When the watchtower Docker container is started, the created configuration file (`<PATH>/config.json` in this example) needs to be passed to the container:
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```bash
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docker run [...] -v <PATH>/config.json:/config.json containrrr/watchtower
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```
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### Share the Docker configuration file
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To pull an image from a private registry, `docker login` needs to be called first, to get access to the registry. The provided credentials are stored in a configuration file called `<PATH_TO_HOME_DIR>/.docker/config.json`. This configuration file can be directly used by watchtower. In this case, the creation of an additional configuration file is not necessary.
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When the Docker container is started, pass the configuration file to watchtower:
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```bash
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docker run [...] -v <PATH_TO_HOME_DIR>/.docker/config.json:/config.json containrrr/watchtower
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```
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When creating the watchtower container via docker-compose, use the following lines:
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```yaml
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version: "3"
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[...]
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watchtower:
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image: index.docker.io/containrrr/watchtower:latest
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volumes:
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- /var/run/docker.sock:/var/run/docker.sock
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- <PATH_TO_HOME_DIR>/.docker/config.json:/config.json
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[...]
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```
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## Credential helpers
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Some private Docker registries (the most prominent probably being AWS ECR) use non-standard ways of authentication.
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To be able to use this together with watchtower, we need to use a credential helper.
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To keep the image size small we've decided to not include any helpers in the watchtower image, instead we'll put the
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helper in a separate container and mount it using volumes.
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### Example
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Example implementation for use with [amazon-ecr-credential-helper](https://github.com/awslabs/amazon-ecr-credential-helper):
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```Dockerfile
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FROM golang:latest
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ENV CGO_ENABLED 0
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ENV REPO github.com/awslabs/amazon-ecr-credential-helper/ecr-login/cli/docker-credential-ecr-login
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RUN go get -u $REPO
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RUN rm /go/bin/docker-credential-ecr-login
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RUN go build \
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-o /go/bin/docker-credential-ecr-login \
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/go/src/$REPO
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WORKDIR /go/bin/
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```
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and the docker-compose definition:
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```yaml
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version: "3"
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services:
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watchtower:
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image: index.docker.io/containrrr/watchtower:latest
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volumes:
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- /var/run/docker.sock:/var/run/docker.sock
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- <PATH_TO_HOME_DIR>/.docker/config.json:/config.json
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- helper:/go/bin
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environment:
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- HOME=/
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- PATH=$PATH:/go/bin
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- AWS_REGION=<AWS_REGION>
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- AWS_ACCESS_KEY_ID=<AWS_ACCESS_KEY>
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- AWS_SECRET_ACCESS_KEY=<AWS_SECRET_ACCESS_KEY>
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volumes:
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helper: {}
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```
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and for `<PATH_TO_HOME_DIR>/.docker/config.json`:
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```json
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{
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"HttpHeaders" : {
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"User-Agent" : "Docker-Client/19.03.1 (XXXXXX)"
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},
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"credsStore" : "osxkeychain",
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"auths" : {
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"xyzxyzxyz.dkr.ecr.eu-north-1.amazonaws.com" : {},
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"https://index.docker.io/v1/": {}
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},
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"credHelpers": {
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"xyzxyzxyz.dkr.ecr.eu-north-1.amazonaws.com" : "ecr-login",
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"index.docker.io": "osxkeychain"
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}
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}
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```
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*Note:* `osxkeychain` can be changed to your prefered credentials helper.
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