Web Redis counter

A web application that implements the rediscounter package. When run it will start a web server that can increase and show the counter's value. It also displays the time of the request and information about the redis server connection.

Requests need to be made to the following paths:

• /incr will increment the counter and then display the resulting value.
• /decer will decrease the counter and then display the resulting value. The counter value will not drop below 0.
• /get will display the current value, without incrementing it.
• /reset will reset the counter to 0.
• /health will return HTTP 200 and display OK or HTTP 500 and display "Redis server is down!" depending on the redis server connection status.
• /metrics will display usage data for the called paths since the server start.
• /crash will shut down the web server.

Building the command

• install Golang or use the provided Vagrant project which includes also VMs with Redis and Vault.
• download the package - go get github.com/slavrd/go-redis-counter
• build the command - go build $(go env GOPATH)/src/github.com/slavrd/go-redis-counter/webcounter

Running the command

The binary accepts the following options. All of them have defaults set so it can potentially be run without using any of them.

• -bind-addr - the address to bind the http server to. Default is 0.0.0.0.
• -html-tpl - path to the go http template rendered by the server. Default is html/index.gohtml.
• -redis-host - the IP address / name of the redis server host. Default is 127.0.0.1.
• -redis-port - the port of the redis server. Default is 6379.
• -redis-pass - the redis server password. Default is "" - no authentication required.
• -redis-db - the redis server db index. Default is 0
• -redis-key - the redis server key to use for storing the counter's value. Default is count

Some parameters can be set using environment variables as well. Precedence is passed flag > environment variable > flag default.

• REDIS_ADDR - can set the redis server host or host:port. If it holds only the host the -redis-port flag (or its default) will be used to complete the address. If it holds host:port and the -redis-port flag is passed it will be ignored unless the -redis-host flag is passed as well.
• REDIS_PASS - can set the redis server password.

The application can also retrieve the redis password from Vault. To enable/configure this the following environment vars need to be set:

• VAULT_TOKEN - the Vault access token. If this is set the application will attempt to retrieve the pass form Vault.
• VAULT_ADDR - the Vault server address. In case the variable is note set the default is https://127.0.0.1:8200.
• VAULT_RP_PATH - the redis password secret path in Vault. Defaults to secret/redispassword.
• VAULT_RP_KEY - the redis password secret key in Vault. Defaults to pass

Note: The application will attempt to retrieve the the password from Vault if and only if VAULT_TOKEN is set. In case it is unable to retrieve the password for some reason - cannot connect to vault, secret does not exits etc. it will retry on increasing intervals of up to 1 min.

In any case the webserver will be started with the redis connection configured based on the values of REDIS_PASS/-redis-pass. Once the password is retrieved from Vault the connection configuration will be overridden.

Examples:

./webcounter will start the server bound on 0.0.0.0, connecting to redis @ 127.0.0.1:6379 with no authentication.

./webcounter -redis-server 192.168.10.11 -redis-pass 'mypass' - will start the server bound on 0.0.0.0, connecting to redis @ 192.168.10.11:6379, authenticating with mypass

REDIS_ADDR="192.168.10.11:6379" ./webcounter -redis-port 1111 - will start the server bound on 0.0.0.0, connecting to redis @ 192.168.10.11:6379 with no authentication.

Current application deployment flow

Note: related repositories containing packer, terraform etc. project code are listed in the root repository readme