By default, watchtower will monitor all containers running within the Docker daemon to which it is pointed (in most cases this
will be the local Docker daemon, but you can override it with the `--host` option described in the next section). However, you
can restrict watchtower to monitoring a subset of the running containers by specifying the container names as arguments when
@ -33,14 +35,16 @@ Some arguments can also reference a file, in which case the contents of the file
This can be used to avoid putting secrets in the configuration file or command line.
The following arguments are currently supported (including their corresponding `WATCHTOWER_` environment variables):
- `notification-url`
- `notification-email-server-password`
- `notification-slack-hook-url`
- `notification-msteams-hook`
- `notification-gotify-token`
- `http-api-token`
- `notification-url`
- `notification-email-server-password`
- `notification-slack-hook-url`
- `notification-msteams-hook`
- `notification-gotify-token`
- `http-api-token`
### Example docker-compose usage
```yaml
secrets:
access_token:
@ -55,6 +59,7 @@ services:
```
## Help
Shows documentation about the supported flags.
```text
@ -65,6 +70,7 @@ Environment Variable: N/A
```
## Time Zone
Sets the time zone to be used by WatchTower's logs and the optional Cron scheduling argument (--schedule). If this environment variable is not set, Watchtower will use the default time zone: UTC.
To find out the right value, see [this list](https://en.wikipedia.org/wiki/List_of_tz_database_time_zones), find your location and use the value in _TZ Database Name_, e.g _Europe/Rome_. The timezone can alternatively be set by volume mounting your hosts /etc/localtime file. `-v /etc/localtime:/etc/localtime:ro`
@ -76,6 +82,7 @@ Environment Variable: TZ
```
## Cleanup
Removes old images after updating. When this flag is specified, watchtower will remove the old image after restarting a container with a new image. Use this option to prevent the accumulation of orphaned images on your system as containers are updated.
Removes anonymous volumes after updating. When this flag is specified, watchtower will remove all anonymous volumes from the container before restarting with a new image. Named volumes will not be removed!
Poll interval (in seconds). This value controls how frequently watchtower will poll for new images. Either `--schedule` or a poll interval can be defined, but not both.
[Cron expression](https://pkg.go.dev/github.com/robfig/cron@v1.2.0?tab=doc#hdr-CRON_Expression_Format) in 6 fields (rather than the traditional 5) which defines when and how often to check for new images. Either `--interval` or the schedule expression
can be defined, but not both. An example: `--schedule "0 0 4 * * *"`
Timeout before the container is forcefully stopped. When set, this option will change the default (`10s`) wait time to the given value. An example: `--stop-timeout 30s` will set the timeout to 30 seconds.
```text
@ -455,10 +488,10 @@ Writes the session results to STDOUT using a stable, machine-readable format (in
By default, watchtower will watch all containers. However, sometimes only some containers should be updated.
There are two options:
- **Fully exclude**: You can choose to exclude containers entirely from being watched by watchtower.
- **Monitor only**: In this mode, watchtower checks for container updates, sends notifications and invokes the [pre-check/post-check hooks](https://watchtower.devcdn.net/lifecycle-hooks/) on the containers but does **not** perform the update.
- **Fully exclude**: You can choose to exclude containers entirely from being watched by watchtower.
- **Monitor only**: In this mode, watchtower checks for container updates, sends notifications and invokes the [pre-check/post-check hooks](https://watchtower.devcdn.net/lifecycle-hooks/) on the containers but does **not** perform the update.
## Full Exclude
## Full Exclude
If you need to exclude some containers, set the _com.centurylinklabs.watchtower.enable_ label to `false`. For clarity this should be set **on the container(s)** you wish to be ignored, this is not set on watchtower.
@ -23,7 +25,6 @@ If you need to exclude some containers, set the _com.centurylinklabs.watchtower.
=== "docker-compose"
``` yaml
version: "3"
services:
someimage:
container_name: someimage
@ -47,7 +48,6 @@ If instead you want to [only include containers with the enable label](https://w
=== "docker-compose"
``` yaml
version: "3"
services:
someimage:
container_name: someimage
@ -78,4 +78,4 @@ Or, it can be specified as part of the `docker run` command line:
docker run -d --label=com.centurylinklabs.watchtower.monitor-only=true someimage
```
When the label is specified on a container, watchtower treats that container exactly as if [`WATCHTOWER_MONITOR_ONLY`](https://watchtower.devcdn.net/arguments/#without_updating_containers) was set, but the effect is limited to the individual container.
When the label is specified on a container, watchtower treats that container exactly as if [`WATCHTOWER_MONITOR_ONLY`](https://watchtower.devcdn.net/arguments/#without_updating_containers) was set, but the effect is limited to the individual container.
Watchtower provides an HTTP API mode that enables an HTTP endpoint that can be requested to trigger container updating. The current available endpoint list is:
- `/v1/update` - triggers an update for all of the containers monitored by this Watchtower instance.
@ -7,7 +9,7 @@ Watchtower provides an HTTP API mode that enables an HTTP endpoint that can be r
To enable this mode, use the flag `--http-api-update`. For example, in a Docker Compose config file:
This is a fork of the really nice project from [containrrr](https://github.com/containrrr) called [watchtower](https://github.com/containrrr/watchtower).
I am not the original author of this project. I just forked it to make some changes to it and keep it up-to-date as properly as I can.
I am not the original author of this project. I just forked it to make some changes to it and keep it up-to-date as properly as I can.
Contributions, tips and hints are welcome. Just open an issue or a pull request. Please be aware that I am by no means a professional developer. I am just a Platform Engineer.
Watchtower is an application that will monitor your running Docker containers and watch for changes to the images that those containers were originally started from. If watchtower detects that an image has changed, it will automatically restart the container using the new image.
With watchtower you can update the running version of your containerized app simply by pushing a new image to the Docker Hub or your own image registry. Watchtower will pull down your new image, gracefully shut down your existing container and restart it with the same options that were used when it was deployed initially.
@ -12,4 +14,3 @@ CONTAINER ID IMAGE STATUS PORTS
```
Every day watchtower will pull the latest _centurylink/wetty-cli_ image and compare it to the one that was used to run the "wetty" container. If it sees that the image has changed it will stop/remove the "wetty" container and then restart it using the new image and the same `docker run` options that were used to start the container initially (in this case, that would include the `-p 8080:3000` port mapping).
Watchtower will detect if there are links between any of the running containers and ensures that things are stopped/started in a way that won't break any of the links. If an update is detected for one of the dependencies in a group of linked containers, watchtower will stop and start all of the containers in the correct order so that the application comes back up correctly.
For example, imagine you were running a _mysql_ container and a _wordpress_ container which had been linked to the _mysql_ container. If watchtower were to detect that the _mysql_ container required an update, it would first shut down the linked _wordpress_ container followed by the _mysql_ container. When restarting the containers it would handle _mysql_ first and then _wordpress_ to ensure that the link continued to work.
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.
environment, watchtower needs to know the credentials to access the registry.
The credentials can be provided to watchtower in a configuration file called `config.json`.
There are two ways to generate this configuration file:
@ -8,7 +10,8 @@ There are two ways to generate this configuration file:
* The configuration file can be created manually.
* Call `docker login <REGISTRY_NAME>` and share the resulting configuration file.
### Create the configuration file manually
## Create the configuration file manually
Create a new configuration file with the following syntax and a base64 encoded username and
password `auth` string:
@ -31,7 +34,7 @@ password `auth` string:
In this special case, the registry domain does not have to be specified
in `docker run` or `docker-compose`. Like Docker, Watchtower will use the
Docker Hub registry and its credentials when no registry domain is specified.
<sub>Watchtower will recognize credentials with `<REGISTRY_NAME>``index.docker.io`,
but the Docker CLI will not.</sub>
@ -40,7 +43,7 @@ password `auth` string:
in both `config.json` and the `docker run` command or `docker-compose` file.
Valid hosts are `localhost[:PORT]`, `HOST:PORT`,
or any multi-part `domain.name` or IP-address with or without a port.
Examples:
* `localhost` -> `localhost/myimage`
* `127.0.0.1` -> `127.0.0.1/myimage:mytag`
@ -66,7 +69,7 @@ When the watchtower Docker container is started, the created configuration file
docker run [...] -v <PATH>/config.json:/config.json beatkind/watchtower
```
### Share the Docker configuration file
## Share the Docker configuration file
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`.
@ -92,14 +95,15 @@ services:
...
```
#### Docker Config path
### Docker Config path
By default, watchtower will look for the `config.json` file in `/`, but this can be changed by setting the `DOCKER_CONFIG` environment variable to the directory path where your config is located. This is useful for setups where the config.json file is changed while the watchtower instance is running, as the changes will not be picked up for a mounted file if the inode changes.
Example usage:
```yaml
version: "3.4"
services:
services:
watchtower:
image: beatkind/watchtower
environment:
@ -110,6 +114,7 @@ services:
```
## Credential helpers
Some private Docker registries (the most prominent probably being AWS ECR) use non-standard ways of authentication.
To be able to use this together with watchtower, we need to use a credential helper.
@ -117,6 +122,7 @@ To keep the image size small we've decided to not include any helpers in the wat
helper in a separate container and mount it using volumes.
### Example
Example implementation for use with [amazon-ecr-credential-helper](https://github.com/awslabs/amazon-ecr-credential-helper):
Use the dockerfile below to build the [amazon-ecr-credential-helper](https://github.com/awslabs/amazon-ecr-credential-helper),
@ -125,30 +131,30 @@ in a volume that may be mounted onto your watchtower container.
By default, watchtower is set-up to monitor the local Docker daemon (the same daemon running the watchtower container itself). However, it is possible to configure watchtower to monitor a remote Docker endpoint. When starting the watchtower container you can specify a remote Docker endpoint with either the `--host` flag or the `DOCKER_HOST` environment variable:
By default, Watchtower will clean up other instances and won't allow multiple instances running on the same Docker host or swarm. It is possible to override this behavior by defining a [scope](https://watchtower.devcdn.net/arguments/#filter_by_scope) to each running instance.
By default, Watchtower will clean up other instances and won't allow multiple instances running on the same Docker host or swarm. It is possible to override this behavior by defining a [scope](https://watchtower.devcdn.net/arguments/#filter_by_scope) to each running instance.
!!! note
- Multiple instances can't run with the same scope;
@ -10,7 +10,7 @@ To define an instance monitoring scope, use the `--scope` argument or the `WATCH
Watchtower is also capable of connecting to Docker endpoints which are protected by SSL/TLS. If you've used _docker-machine_ to provision your remote Docker host, you simply need to volume mount the certificates generated by _docker-machine_ into the watchtower container and optionally specify `--tlsverify` flag.
The _docker-machine_ certificates for a particular host can be located by executing the `docker-machine env` command for the desired host (note the values for the `DOCKER_HOST` and `DOCKER_CERT_PATH` environment variables that are returned from this command). The directory containing the certificates for the remote host needs to be mounted into the watchtower container at _/etc/ssl/docker_.
When watchtower detects that a running container needs to be updated it will stop the container by sending it a SIGTERM signal.
If your container should be shutdown with a different signal you can communicate this to watchtower by setting a label named _com.centurylinklabs.watchtower.stop-signal_ with the value of the desired signal.
Watchtower is itself packaged as a Docker container so installation is as simple as pulling the `beatkind/watchtower` image. If you are using ARM based architecture, pull the appropriate `beatkind/watchtower:armhf-<tag>` image from the [beatkind Docker Hub](https://hub.docker.com/r/beatkind/watchtower/tags/).
Since the watchtower code needs to interact with the Docker API in order to monitor the running containers, you need to mount _/var/run/docker.sock_ into the container with the `-v` flag when you run it.
@ -41,8 +43,8 @@ docker run -d \
If you mount `config.json` in the manner above, changes from the host system will (generally) not be propagated to the
running container. Mounting files into the Docker daemon uses bind mounts, which are based on inodes. Most
applications (including `docker login` and `vim`) will not directly edit the file, but instead make a copy and replace
the original file, which results in a new inode which in turn _breaks_ the bind mount.
**As a workaround**, you can create a symlink to your `config.json` file and then mount the symlink in the container.
the original file, which results in a new inode which in turn _breaks_ the bind mount.
**As a workaround**, you can create a symlink to your `config.json` file and then mount the symlink in the container.
The symlinked file will always have the same inode, which keeps the bind mount intact and will ensure changes
to the original file are propagated to the running container (regardless of the inode of the source file!).
@ -52,7 +54,7 @@ from a private repo on the GitHub Registry and monitors it with watchtower. Note
Jan Rundshagen
9 months ago
committed by