Golang

Using gin

codegangsta/gin is a live reload utility for Go web servers. It can run any main.go file and restart it when dependent code changes. gin runs a webserver on it’s own and proxies requests to the actual webserver. The only requirement is that the actual webserver should take a PORT environment variable and listen on that address so that gin can set it arbitrarily.

Let’s look at a typical Go microservice (refer hasura/hello-golang-raw).

 .
├── Dockerfile
├── k8s.yaml
└── src
    └── main.go

If you run gin --path src --port 8080 run main.go, a webserver will be started in port 8080 and it will restart automatically for any code change.

Dockerfile
# Step 1: use golang base image
FROM golang:1.8.5-jessie

# Step 2: install gin
RUN go get github.com/codegangsta/gin

# Step 3: setup the working directory
WORKDIR /go/src/app

# Step 4: add source code
ADD src src

# Step 5: start a gin server
CMD ["gin", "--path", "src", "--port", "8080", "run", "main.go"]

Step 4 copies the source code from src to /gp/src/app/src. Sync for these directories can be done using the following command (assuming name of the microservice is api):

$ hasura microservice sync api microservices/api/src:/go/src/app/src

Keep the command running in a terminal. Open the microservice in a browser, using another terminal window:

$ hasura microservice open api

Make some changes to main.go and save. Refresh the browser and voila! You can see that changes live in the browser tab.