The etcd cluster has shared-nothing nodes. The cluster has a leader and followers, with one node acting as the cluster's leader. The Raft algorithm determines the leader node at run-time. The leader node casts votes against followers in response to requests. The leader commits the request and asks followers to commit if the majority of nodes concur. Any node in the cluster may receive a request from an etcd client. If the client sends a request to a follower, the follower relaysthe request to a leader node.
How to interact with etcd?
You can communicate with etcd through the etcd command-line client (etcdctl), the HTTP/gRPC API, or one of the numerous client libraries for various programming languages. To use etcdctl, you can follow the instructions below:
1. Since etcdctl is frequently included in the etcd distribution, installing etcd is usually required before installing etcdctl. Use the following command to install etcd for Ubuntu/Debian:
sudo apt-get update
sudo apt-get install etcd
2. After the installation is complete, you can verify that etcdctl is installed by running the following command:
3. To connect to your etcd cluster, etcdctl must be configured. The endpoint of your etcd cluster is typically specified using environment variables like ETCDCTL_ENDPOINTS.
4. To set the ETCDCTL_API environment variable to specify a particular API version for the etcdctl command-line client, you can use the following syntax:
export ETCDCTL_API=<API version>
Setting the ETCDCTL_API environment variable to the desired API version will instruct etcdctl to use that version when communicating with the etcd cluster. The etcdctl command-line client supports two major API versions: version 2 and version 3. In newer versions of etcd, version 3 is the default API version.
5. Once configured, etcdctl can be used to communicate with your etcd cluster by executing commands like etcdctl put, etcdctl get, etc.
etcdctl set <key> <value> #Setting a Key-Value Pair for version 2 API
etcdctl put <key> <value> #Setting a Key-Value Pair for version 3 API
etcdctl get <key> #Getting a Value by Key
etcdctl del <key> #Deleting a Key
etcdctl watch <key> #Watching for Changes
Here is the configuration for monitoring etcd that uses the Instana plug-in. This configuration specifies the paths to the required certificate and key files for establishing a secure connection to the etcd cluster. The CA Certificate is used to verify the authenticity of the etcd server's certificate.
The Client Certificate is used by Instana to authenticate itself to the etcd server. It should be a valid certificate that has been signed by the CA certificate. Client key is the private key used for cryptographic operations to establish a secure connection.
Metrics and dashboards
To ensure the dependability and stability of your distributed systems, it's crucial to monitor etcd performance, especially when it's used as a crucial component in platforms like Kubernetes. A range of performance indicators are offered by etcd to track the functions and overall health of the etcd cluster.
The details provided by the Etcd dashboard includes the number of requests that are sent and received, the amount of incoming and outgoing data in bytes, the number of keys that expire each second, the number of watchers, and the number of operations such as sets, gets, create, update, delete, compare and swap, and compare and delete etc.
There are currently two dashboards for etcd, one for metrics gathered from /v2 endpoints and the other for metrics gathered from /v3 endpoints.
The v2 dashboard provides information like the cluster version, server version, and the number of unsuccessful and successful database operations.
The v3 dashboard includes Additional information like the Api version and counts of various database operations as compared to v2 dashboard.
Monitoring etcd using Instana offers a robust and comprehensive solution to ensure the reliability, performance, and health of your etcd clusters. It provides a strong solution for assuring the efficiency and dependability of your distributed etcd clusters. You can proactively manage your etcd infrastructure with its real-time visibility, security, and actionable analytics, and it will provide a solid basis for your distributed applications.