Implemented RetryJoin on AzureRM

[leowmjw]

Addresses #2667; please provide feedback, suggestions and guidance. @slackpad for your consideration.

DONE:

• Implementation, passed unit tests and passed manual deploy into existing Consul cluster.
• Update docs, with examples.
• Incorporated into Nomad-Box (https://github.com/leowmjw/nomad-box) so can auto retry-join

Binaries at: https://gist.github.com/leowmjw/fe8344b5b8e7c0d000f18335774e7ef3

Changesets:

• Azure libs for network vendored in with go vendor; including reps
• Implemented and test passed for config decoding of RetryJoinAzure
• Added the RetryJoinAzure struct which has the mapstructure to config file; including top level
• Implement the merge logic for all the fields in RetryJoinAzure struct
• Implemented and test passed for discovering of Azure Hosts using tags; for now only Public Environment
• Added 2 additional cli config for tag name + value; credentials need to be passed via config file
• Cleaned up discover Azure Hosts to its bare minimum and try to be as robust in handling nil pointers
• Refactored the retryJoin so standardised to detect which is enabled ec2, gee or azure and take action accordingly

[magiconair]

@leowmjw I'm going to take a look at this. Could you please rebase your branch, resolve any conflicts and force push the changes? I've recently moved some code around. The retry/join code now lives in separate files per provider. This will make the review easier.

[leowmjw]

@magiconair thanks for the heads-up; yeah I noticed the code being refactored :P I'll fix it up later this week when I get some time and ping you for review.

[magiconair]

@leowmjw ping

[leowmjw]

@magiconair Ready for your review. Thanks!

Simple usage via Terraform can be found at: https://github.com/leowmjw/nomad-box/blob/master/terraform/templates/base.tpl

# Extract the IP address from the determined interface
CONSUL_CLIENT_INTERFACE="eth0"
CONSUL_CLIENT_ADDRESS=$(ip -o -4 addr list $CONSUL_CLIENT_INTERFACE | head -n1 | awk '{print $4}' | cut -d/ -f1)
# Use that address to setup the HTTP endpoint so that it is reachable from within Docker container
cat > ./consul.d/config.json <<EOF
{
    "addresses": {
        "http": "$${CONSUL_CLIENT_ADDRESS}"
    }
}
EOF

cat > ./consul.d/retry.json <<EOF
{
    "retry_join_azure": {
                "tag_name": "type",
                "tag_value": "Foundation",
                "subscription_id": "${vars_subscription_id}",
                "tenant_id": "${vars_tenant_id}",
                "client_id": "${vars_client_id}",
                "secret_access_key": "${vars_secret_access_key}"
        }
    }
}
EOF

# Extract the IP address from the determined interface
CONSUL_BIND_INTERFACE="eth0"
CONSUL_BIND_ADDRESS=$(ip -o -4 addr list $CONSUL_BIND_INTERFACE | head -n1 | awk '{print $4}' | cut -d/ -f1)

# Start up the Consul agent
/opt/consul/consul agent -server -ui -bootstrap-expect=${vars_bootstrap_expected} -data-dir=/tmp/consul \
  -config-dir=./consul.d -bind=$${CONSUL_BIND_ADDRESS} &

[magiconair]

Thx. I have a look on Tue or Wed.

[magiconair]

@leowmjw I've rebased your change again and split out the vendored libs into separate commits. Could you have a look and test whether it works, please?

[leowmjw]

Latest test binaries in: https://gist.github.com/leowmjw/fe8344b5b8e7c0d000f18335774e7ef3/revisions

Next to test final in Nomad Box to ensure vendor lib did not break anything.

[leowmjw]

@magiconair Just to confirm; it works fine; auto join cluster as per below:

$ CONSUL_HTTP_ADDR=http://acme-nomad-dev-foundation-node-2:8500 ./consul members
Node                              Address        Status  Type    Build     Protocol  DC
acme-nomad-dev-foundation-node-1  10.0.1.4:8301  alive   server  0.8.2dev  2         dc1
acme-nomad-dev-foundation-node-2  10.0.2.4:8301  alive   server  0.8.2dev  2         dc1
acme-nomad-dev-foundation-node-3  10.0.3.4:8301  alive   server  0.8.2dev  2         dc1

[slackpad]

Thank you @leowmjw - appreciate the final check!

[magiconair]

Awesome @leowmjw . Thanks for the patch and for the testing.