cloudready/consul repository overview

⁠docker-consul-agent

docker-consul-agent

⁠Running Consul for Development

In-memory Consul server agent with default bridge networking and no services exposed on the host For development, should not be used in production

command: ["agent", "-dev", "-client", "0.0.0.0"]

Join the existing node

command: ["agent", "-dev", "-join=<root-agent-ip>"]

⁠Running Consul Agent in Client Mode

This runs a Consul client agent sharing the host's network and advertising the external IP address to the rest of the cluster. Note that the agent defaults to binding its client interfaces to 127.0.0.1, which is the host's loopback interface. This would be a good configuration to use if other containers on the host also use --net=host, and it also exposes the agent to processes running directly on the host outside a container, such as HashiCorp's Nomad.

command: ["agent", "-bind=<external ip>", "-retry-join=<root agent ip>", "-retry-interval=30s", "-retry-max=0"]

If you want to expose the Consul interfaces to other containers via a different network, such as the bridge network, use the -client option for Consul:

command: ["agent", "-bind=<external ip>", "-client=<bridge ip>", "-retry-join=<root agent ip>", "-retry-interval=30s", "-retry-max=0"]

⁠Running Consul Agent in Server Mode

This runs a Consul server agent sharing the host's network. All of the network considerations and behavior we covered above for the client agent also apply to the server agent. A single server on its own won't be able to form a quorum and will be waiting for other servers to join.

command: ["agent", "-server", "-bind=<external ip>", "-retry-join=<root agent ip>", "-retry-interval=30s", "-retry-max=0", "-bootstrap-expect=<number of server agents>"]

⁠Exposing Consul's DNS Server on Port 53

By default, Consul's DNS server is exposed on port 8600. Because this is cumbersome to configure with facilities like resolv.conf, you may want to expose DNS on port 53. Consul 0.7 and later supports this by setting an environment variable that runs setcap on the Consul binary, allowing it to bind to privileged ports. Note that not all Docker storage backends support this feature (notably AUFS).

command: ["agent", "-dns-port=53", "-recursor=8.8.8.8", "-bind=<bridge ip>"]

Test DNS

docker run -i --dns=<bridge ip> -t ubuntu sh -c "apt-get update && apt-get install -y dnsutils && dig consul.service.consul"

Test Docker for Mac

nslookup host.docker.internal
nslookup docker.for.mac.host.internal
#nslookup docker.for.win.host.internal

nslookup gateway.docker.internal
nslookup docker.for.mac.gateway.internal
#nslookup docker.for.win.gateway.internal

nslookup docker.for.mac.http.internal
#nslookup docker.for.win.http.internal

Test service resolution

dig @localhost config-server.service.consul.
dig @localhost config-server.service.consul. ANY
dig @localhost config-server.service.consul. SRV

Http API

http://127.0.0.1:8500/v1/agent/members⁠ http://127.0.0.1:8500/v1/catalog/nodes⁠ http://127.0.0.1:8500/v1/catalog/services⁠ http://127.0.0.1:8500/v1/catalog/service/config-server⁠

see: https://github.com/hashicorp/docker-consul⁠

see: https://hub.docker.com/r/library/consul/⁠

see: https://www.consul.io/docs/agent/basics.html⁠