Gradle脚本SSH部署Oracle Cloud Ubuntu服务器遇JSch Auth fail异常

使用Gradle脚本通过SSH连接Oracle Cloud的Ubuntu服务器部署JWT认证服务时，持续触发以下异常：

org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':deploy'.
com.jcraft.jsch.JSchException: Auth fail

部署任务代码 #

task("deploy") {
    dependsOn("clean", "shadowJar")
    ant.withGroovyBuilder {
        doLast {
            val knownHosts = File.createTempFile("knownhosts", "txt")
            val user = "ubuntu"
            val host = "129.159.251.61"
            val key = file("keys/private-key")
            val jarFileName = "com.jwtauth.ktor-jwt-auth-$version-all.jar"
            try {
                "scp"(
                    "file" to file("build/libs/$jarFileName"),
                    "todir" to "$user@$host:/root/jwtauth",
                    "keyfile" to key,
                    "trust" to true,
                    "knownhosts" to knownHosts
                )
                "ssh"(
                    "host" to host,
                    "username" to user,
                    "keyfile" to key,
                    "trust" to true,
                    "knownhosts" to knownHosts,
                    "command" to "sudo mv /root/jwtauth/$jarFileName /root/jwtauth/jwtauth.jar"
                )
                "ssh"(
                    "host" to host,
                    "username" to user,
                    "keyfile" to key,
                    "trust" to true,
                    "knownhosts" to knownHosts,
                    "command" to "sudo systemctl stop jwtauth"
                )
                "ssh"(
                    "host" to host,
                    "username" to user,
                    "keyfile" to key,
                    "trust" to true,
                    "knownhosts" to knownHosts,
                    "command" to "sudo systemctl start jwtauth"
                )
            } finally {
                knownHosts.delete()
            }
        }
    }
}

已尝试的解决方案 #

• 确认私钥以-----BEGIN RSA PRIVATE KEY-----开头，符合JSch要求；
• 核对连接凭证与Putty连接时完全一致；
• 确认对应公钥已正确添加至服务器~/.ssh/authorized_keys；
• 更换多台服务器及多组密钥对测试，问题依旧；
• 修改sshd_config将PasswordAuthentication设为yes（默认值为no）

内容的提问来源于stack exchange，提问作者randomdude0