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Configuration

There are three groups of variables required to build BlockScout. The first is required to create infrastructure, the second to build BlockScout instances and the third is required both for infra and BS itself. For your convenience we have divided variable templates into three files accordingly - infrastructure.yml.example, blockscout.yml.example and all.yml.example . Also we have divided those files to place them in the group_vars and in host_vars folders, so you will not have to repeat some of the variables for each host/group. To deploy BlockScout, you will setup the following set of files for each instance: 
/
| - group_vars
|   | - group.yml (combination of [blockscout+infrastructure+all].yml.example)
|   | - all.yml (optional, one for all instances)
| - host_vars
|   | - host.yml (combination of [blockscout+infrastructure+all].yml.example)
| - hosts (one for all instances)
The subsections below describe the variables you may want to adjust.

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Infrastructure Variables

  • terraform_location is an address of the Terraform binary on the builder;
  • dynamodb_table represents the name of table that will be used for Terraform state lock management;
  • If ec2_ssh_key_content variable is not empty, Terraform will try to create EC2 SSH key with the ec2_ssh_key_name name. Otherwise, the existing key with ec2_ssh_key_name name will be used;
  • instance_type defines a size of the Blockscout instance that will be launched during the deployment process;
  • vpc_cidr, public_subnet_cidr, db_subnet_cidr represents the network configuration for the deployment. Usually you want to leave it as is. However, if you want to modify it, please, expect that db_subnet_cidr represents not a single network, but a group of networks started with defined CIDR block increased by 8 bits.
Example: Number of networks: 2 db_subnet_cidr: “10.0.1.0/16” Real networks: 10.0.1.0/24 and 10.0.2.0/24
  • An internal DNS zone withdns_zone_name name will be created to take care of BlockScout internal communications;
  • The root_block_size is the amount of storage on your EC2 instance. This value can be adjusted by how frequently logs are rotated. Logs are located in /opt/app/logs of your EC2 instance;
  • Each of the db_* variables configures the database for each chain. Each chain will have the separate RDS instance;
  • instance_type represent the size of the EC2 instance to be deployed in production;
  • use_placement_group determines whether or not to launch BlockScout in a placement group.

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BlockScout Variables

  • blockscout_repo - a direct link to the BlockScout repo;
  • branch - maps branch at blockscout_repo to each chain;
  • Specify the merge_commit variable if you want to merge any of the specified chains with the commit in the other branch. Usually used to update production branches with the releases from master branch;
  • skip_fetch - if this variable is set to true , BlockScout repo will not be cloned and the process will start from building the dependencies. Use this variable to prevent playbooks from overriding manual changes in cloned repo;
  • ps_* variables represents a connection details to the test Postgres database. This is not installed automatically, so make sure ps_* credentials are valid before starting the deployment;

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Common (All) Variables

  • ansible_host - is an address where BlockScout will be built. If this variable is set to localhost, also set ansible_connection to local for better performance.
  • chain variable set the name of the network (Kovan, Core, xDAI, etc.). Will be used as part of the infrastructure resource names.
  • env_vars represents the set of environment variables used by BlockScout. They are available here.
    • One can define BUILD_* set of the variables, where asterisk stands for any environment variables. All variables defined with BUILD_* will override default variables while building the dev server.
  • aws_access_key and aws_secret_key is a credentials pair that provides access to AWS for the deployer; You can use the aws_profile instead. In that case, AWS CLI profile will be used. Also, if none of the access key and profile provided, the default AWS profile will be used. The aws_region should be left at us-east-1 as some of the other regions fail for different reasons;
  • backend variable defines whether deployer should keep state files remote or locally. Set backend variable to true if you want to save state file to the remote S3 bucket;
  • upload_config_to_s3 - set to true if you want to upload config all.yml file to the S3 bucket automatically after the deployment. Will not work if backend is set to false;
  • upload_debug_info_to_s3 - set to true if you want to upload full log output to the S3 bucket automatically after the deployment. Will not work if backend is set to false.
Locally logs are stored at log.txt which is not cleaned automatically. Do not forget to clean manually or use the clean.yml playbook
  • bucket represents a globally unique name of the bucket where your configs and state will be stored. It will be created automatically during the deployment;
a chain name SHOULD NOT be more than 5 characters. Otherwise, it will throw an error because the aws load balancer name should not be greater than 32 characters.