Run the Ganache Cli Inside the Docker Container

Monday, April 1, 2019 • 4 minutes to read

In this article, we’ll run the ganache-cli inside the docker container and then we will connect it to the Metamask and transfer some Ether from one account to another.

Prerequisites:

  1. Docker installed in your machine. Please check out this link and install which fits with your OS.
  2. The Metamask plugin installed to your browser. Please check out this link and follow the instructions to install it.

Lets first create the project directory by name docker-ganache.

Inside the docker-ganache, create a file named Dockerfile.

The Dockerfile doesn’t require a file extension and D must be uppercase.

Our file structure will look like this

- docker-ganache
  - Dockerfile

Dockerfile is the file where we’ll define all the commands required to create a ganache-cli docker image.

Docker can build images automatically by reading the instructions from a Dockerfile.


Open the Dockerfile in any editor and paste the below code

# node:alpine will be our base image to create this image
FROM node:alpine

# Set the /app directory as working directory
WORKDIR /app

# Install ganache-cli globally
RUN npm install -g ganache-cli

# Set the default command for the image
CMD ["ganache-cli", "-h", "0.0.0.0"]

Let’s take a dip into the code and explore what it is actually doing.

The Docker container requires Node.js installed in it to install the ganache-cli.

The node:alpine is the base image in which the latest Node.js is pre-installed.

What does alpine means?

It is the minimum requirement needed for Node.js. It includes the required libraries. For more information please visit this link.

The base image already has a filesystem for node:alpine

app    dev    home   media  opt    root   sbin   sys    usr
bin    etc    lib    mnt    proc   run    srv    tmp    var

The second step WORKDIR /app we are instructing the Dockerfile to use /app folder as the working directory for this image

The third step RUN npm install -g ganache-cli installs the ganache-cli globally.

The last step CMD ["ganache-cli","-h","0.0.0.0"]

When this image run there must be a default command for this or else you have to manually tell what it should do.

ganache-cli -h 0.0.0.0 is the default command for this image. When this image run it will run this default command.

Ganache-cli’s default host is 127.0.0.1 but for docker instance it is 0.0.0.0

Please refer to this link. for more information on ganache-cli flags like -h


Lets now build the image. Open the terminal or CLI and make sure you’re in the docker-ganache directory

Run the below command to build the Dockerfile

docker build .

Thanks to KC Tam for suggesting to use the tag in docker build command.

docker build -t ganache .

You can use tags for the image as image name instead of using an image ID like 7726b19a7bff .

To learn more about image tags please visit this link.

The first time it runs, it might take some time. After it completes, you will likely see the output similar to the image below.

Your output might be slightly different than this. In my case, I have tested it a couple of times previously so everything was saved in the cache memory.

Check the output carefully.

Successfully built 7726b19a7bff

This is the image ID of Dockerfile what we just built. Great all the setup is done, now let’s test it.


Run the docker image and start a container

docker run -p 8545:8545 7726b19a7bff

Or

docker run -p 8545:8545 ganache

In my case 7726b19a7bff is the image ID. You should run your matching ID or the image tag ganache.

What is -p 8545:8545 doing here?

When ganache-cli run on 8545 port, this port is not exposed out of the container. To access this -p 8545:8545 flag expose the 8545 port on 8545 port.

To explain it further, take this example:

Whenever any request points to port 3000, it will redirect the request to container’s 8545 port. It is not compulsory that the other port number has to be the same as the container.

--publish , -p Publish a container’s port(s) to the host

For more information please refer to this link.

After running the command you’ll see the output like this

If you see output like this then you’re on right path.


Let’s connect our ganache-cli to Metamask. Open your browser and Metamask and select the Localhost 8545 network.

Metamask it now connected to docker-ganache.

Let’s import one account to the Metamask. Copy the private key of an account from the running ganache instance.

From Metamask menu click on “Import Account”.

Paste the private key and import. After importing you will see 100 ETH in the account.

Let’s send some ether to another account

  • Click on Send
  • Select Account 1 in To field
  • Enter 10 in the Amount field
  • Select Next and Confirm

Once the transaction is confirmed, check the Account 1 and Account 2.

Account 2 is 89.9998 something. The additional missing ETH is the fee paid for the transaction.

Conclusion

You successfully connected to the ganache-cli running inside the Docker container and submitted a transaction using the Metamask.


Tutorial2019Blockchaintutorialblockchainganacheethereum

Create an Ethereum Dapp with React and Docker

Deploy Angular application on Azure Web Service