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Adds a note about the entrypoint changing ownsership of config and data dirs.

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James Phillips 2016-09-14 15:53:12 -07:00
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@ -27,9 +27,9 @@ Consul always runs under [dumb-init](https://github.com/Yelp/dumb-init), which h
Running the Consul container with no arguments will give you a Consul server in [development mode](https://www.consul.io/docs/agent/options.html#_dev). The provided entry point script will also look for Consul subcommands and run `consul` as the correct user and with that subcommand. For example, you can execute `docker run consul members` and it will run the `consul members` command inside the container. The entry point also adds some special configuration options as detailed in the sections below when running the `agent` subcommand. Any other command gets `exec`-ed inside the container under `dumb-init`. Running the Consul container with no arguments will give you a Consul server in [development mode](https://www.consul.io/docs/agent/options.html#_dev). The provided entry point script will also look for Consul subcommands and run `consul` as the correct user and with that subcommand. For example, you can execute `docker run consul members` and it will run the `consul members` command inside the container. The entry point also adds some special configuration options as detailed in the sections below when running the `agent` subcommand. Any other command gets `exec`-ed inside the container under `dumb-init`.
The container exposes `VOLUME /consul/data`, which is a path were Consul will place its persisted state. This isn't used in any way when running in development mode. For client agents, this stores some information about the cluster and the client's health checks in case the container is restarted. For server agents, this stores the client information plus snapshots and data related to the consensus algorithm and other state like Consul's key/value store and catalog. For servers it is highly desirable to keep this volume's data around when restarting containers to recover from outage scenarios. The container exposes `VOLUME /consul/data`, which is a path were Consul will place its persisted state. This isn't used in any way when running in development mode. For client agents, this stores some information about the cluster and the client's health checks in case the container is restarted. For server agents, this stores the client information plus snapshots and data related to the consensus algorithm and other state like Consul's key/value store and catalog. For servers it is highly desirable to keep this volume's data around when restarting containers to recover from outage scenarios. If this is bind mounted then ownership will be changed to the consul user when the container starts.
The container has a Consul configuration directory set up at `/consul/config` and the agent will load any configuration files placed here by binding a volume or by composing a new image and adding files. Alternatively, configuration can be added by passing the configuration JSON via environment variable `CONSUL_LOCAL_CONFIG`. The container has a Consul configuration directory set up at `/consul/config` and the agent will load any configuration files placed here by binding a volume or by composing a new image and adding files. Alternatively, configuration can be added by passing the configuration JSON via environment variable `CONSUL_LOCAL_CONFIG`. If this is bind mounted then ownership will be changed to the consul user when the container starts.
Since Consul is almost always run with `--net=host` in Docker, some care is required when configuring Consul's IP addresses. Consul has the concept of its cluster address as well as its client address. The cluster address is the address at which other Consul agents may contact a given agent. The client address is the address where other processes on the host contact Consul in order to make HTTP or DNS requests. You will typically need to tell Consul what its cluster address is when starting so that it binds to the correct interface and advertises a workable interface to the rest of the Consul agents. You'll see this in the examples below as the `-bind=<external ip>` argument to Consul. Since Consul is almost always run with `--net=host` in Docker, some care is required when configuring Consul's IP addresses. Consul has the concept of its cluster address as well as its client address. The cluster address is the address at which other Consul agents may contact a given agent. The client address is the address where other processes on the host contact Consul in order to make HTTP or DNS requests. You will typically need to tell Consul what its cluster address is when starting so that it binds to the correct interface and advertises a workable interface to the rest of the Consul agents. You'll see this in the examples below as the `-bind=<external ip>` argument to Consul.