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How to install and configure consul? Many novices are not very clear about this. In order to help you solve this problem, the following editor will explain it in detail. People with this need can come and learn. I hope you can gain something.

Consul simplifies the process of registering and discovering services in a distributed environment through HTTP or DNS interfaces. Support for external SaaS providers, etc.

Some key features provided by consul:

Service discovery:consul makes it easy to register and discover services through DNS or HTTP interfaces, as can some external services, such as those provided by saas.

Health checking: health check enables consul to quickly alert operations in the cluster. Integration with service discovery can prevent services from being forwarded to failed services.

Key/value storage: a system for storing dynamic configurations. Provides a simple HTTP interface that can be operated anywhere.

Multi-datacenter: no complex configuration is required to support any number of areas (data centers).

Official website: https://www.consul.io/

System environment: CentOS release 6.5 (Final) x64

Download address of the latest version of consul

Https://releases.hashicorp.com/consul/0.6.4/consul_0.6.4_linux_amd64.zip

Download and decompress, there is only one consul executable file, execute

[root@localhost consul-0.6.4] # consul usage: consul [--version] [--help] [] Available commands are: agent Runs a Consul agent configtest Validate config file event Fire a new event exec Executes a command on Consul nodes force-leave Forces a member of the cluster to enter the "left" state info Provides debugging information for operators join Tell Consul agent to join cluster keygen Generates a new encryption key keyring Manages gossip layer encryption Keys leave Gracefully leaves the Consul cluster and shuts down lock Execute a command holding a lock maint Controls node or service maintenance mode members Lists the members of a Consul cluster monitor Stream logs from a Consul agent reload Triggers the agent to reload configuration files rtt Estimates network round trip time between nodes version Prints the Consul version watch Watch for changes in Consul

Among them, the most commonly used command is agent

Enter consul agent-h to view help. The common parameters are explained as follows:

-advertise: notification presentation address is used to change the address we present to other nodes in the cluster. In general,-bind address is the presentation address.

-bootstrap: used to control whether a server is in bootstrap mode. Only one server in a datacenter can be in bootstrap mode. When a server is in bootstrap mode, it can be elected as raft leader.

-bootstrap-expect: the number of server nodes expected to be provided in a datacenter. When this value is provided, consul will not boot the entire cluster until the specified number of sever is reached. This tag cannot be shared with bootstrap.

-bind: this address is used for communication within the cluster. All nodes in the cluster must be accessible to the address. The default is 0.0.0.0.

-which client address client:consul is bound to. This address provides services such as HTTP, DNS, RPC, etc. The default is 127.0.0.1.

-config-file: explicitly specify which configuration file to load

-config-dir: configuration file directory, in which all files ending in .json will be loaded

-data-dir: provide a directory to store the status of agent. This directory is required for all agent permits. The directory must be stable and continue to exist after the system reboot.

-dc: this tag controls the name of the datacenter allowed by agent. The default is dc1.

-encrypt: specify secret key to encrypt consul during communication. Key can be generated through consul keygen. Nodes in the same cluster must use the same key.

-join: add the ip address of a launched agent, and you can specify multiple agent addresses multiple times. If consul cannot be added to any specified address, agent will fail to start, and by default agent will not join any nodes when it starts.

-retry-join: similar to join, but allows you to try after the first failure.

-retry-interval: the time interval between two join. Default is 30s.

-retry-max: the number of attempts to repeat join. The default is 0, that is, unlimited attempts.

-the level of log information displayed after log-level:consul agent starts. Default is info. Optional: trace, debug, info, warn, err.

-node: the name of the node in the cluster, which must be unique in a cluster. The default is the hostname of the node.

-version of the protocol used by protocol:consul

-rejoin: causes consul to ignore the previous departure and still try to join the cluster after starting again.

-server: defines that agent runs in server mode. Each cluster has at least one server. It is recommended that each cluster has no more than 5 server.

-syslog: enable the Syslog feature, which only takes effect on linux/osx

-ui-dir: provides the path where web ui resources are stored, and the directory must be readable

-pid-file: provides a path to store the pid file, which can be used for SIGINT/SIGHUP (shutdown / update) agent

To implement the registration and discovery of services using the services provided by consul, we need to establish a consul cluster.

In the consul scenario, consul's agent is deployed and run on each node that provides services, and the collection of all running consul agent nodes forms the consul cluster.

Consul agent has two modes of operation: server and client. The server and client here are only the distinction at the consul cluster level and have nothing to do with the application services built on top of cluster.

Consul agent nodes running in server mode are used to maintain the state of the consul cluster

Officials recommend that each consul cluster have at least three or more agent,client nodes running on the server mode.

Here we take the installation of three nodes as an example, and the environment is configured as follows

192.168.1.100 runs in server mode

192.168.1.101192.168.1.102 runs in client mode

One: configure consul

Extract the file downloaded above, copy the consul to the / opt/consul directory, and then add the / opt/consul directory to the environment variable (configure the three nodes in turn)

Two: run

1: above the 192.168.1.100 node

Cd / opt/consulmkdir dataconsul agent-server-bootstrap-bind=0.0.0.0-client=192.168.1.100-data-dir=data-ui-node=192.168.1.100

In this way, a node is started

2: above the 192.168.1.101 node

Cd / opt/consulmkdir dataconsul agent-bind=0.0.0.0-client=192.168.1.101-data-dir=data-node=192.168.1.101-join=192.168.1.100

3: above the 192.168.1.102 node

Cd / opt/consulmkdir dataconsul agent-bind=0.0.0.0-client=192.168.1.102-data-dir=data-node=192.168.1.102-join=192.168.1.100

After all the nodes have been started

Visit http://192.168.1.100:8500/ to view the management page of the consul cluster

Execute consul members on any node to view the cluster node information

This is executed on the 192.168.1.100 node

[root@localhost consul-0.6.4] # consul members-rpc-addr=192.168.1.100:8400 Node Address Status Type Build Protocol DC 192.168.1.101 192.168.1.101 192.168.1.101 alive client 0.6.4 2 dc1 192.168.1.102 192.168.1.102 dc1 8301 alive client 0.6.4 2 dc1 192.168.1.100 192.168.1.100 rpc-addr=192.168.1.100:8400 Node Address Status Type Build Protocol DC 8301 alive server 0.6.4 2 dc1

Close the node

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